Switch device with improved contact structure



July 27, 1965 R. c. LINGENFELTER 3,197,599

SWITCH DEVICE WITH IMPROVED CONTACT STRUCTURE Filed Oct. 8, 1962 4 Sheets-Sheet 1 Fig.1.

Fig. 3 WiTNESSES: lh JVENTOR QWGU-Q Q Robert C. Lmgenfelter AT TOR N E? July 27, 1965 R. c. LINGENFELTER 3,197,599

SWITCH DEVICE WITH IMPROVED CONTACT STRUCTURE 4 Sheets-Sheet 2 Filed Oct. 8, 1962 July 27, 1965 R. c. LINGENFELTER 3,197,599

SWITCH DEVICE WITH IMPROVED CONTACT STRUCTURE Filed Oct. 8, 1962 4 Sheets-Sheet 3 HV LV HV LV July 27, 1965 R. c. LINGENFELTER 7,

SWITCH DEVICE WITH IMPROVED CONTACT STRUCTURE Filed Oct. 8, 1962 4 Sheets-Sheet 4 United States Patent 3,l97,5 SWlTtJH DEVIQE Wt H EMPRSVED CGNTACT STERUQTURE Robert C. Lingenfelter, Sharon, Pa, assignor to Westing- Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Filed Oct. 8, i962, Ser. No. 228,936

1 Claims. (Q. 209-178) This invention relates generally to switch structures and more particularly to a switch structure in the form of a transformer tap changer.

in certain types of switches, and particularly in switches wherein the movable contact arm is a cantilever structure that bridges two contacts of a stationary contact structure, it is important to not only provide contact pressure when the contacts are in the closed position; but also to provide means for alignin the contacts during a closing operation.

Accordingly, it is an object of this invention to provide a switch structure with improved means for aligning the contacts during a closing operation and for maintaining contact pressure when the contacts are in the closed position.

Many transformers are operated under conditions which require that the voltage ratio between the primary and secondary windings be adjustable. This may be done by providing one of the transformer windings with a plurality of tap connections connected between suitable tap points on the winding and certain switch contact members so that by operation of a tap changer switch a selected number of turns of the windin. may be excluded from or included in the winding circuit, thus varying the effective number of turns in the Winding.

Another object of this invention is to provide an improved transformer tap changer switch comprising a plurality of stationary contact structures and a movable bridging contact structure with improved means for aligning the contacts and for providing contact pressure when the contacts are in the closed position.

Other objects of this invention will be apparent from the following description when taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevational view, partly in section, of a part of a transformer provided with a tap changer switch constructed in accordance with principles of this invention;

PEG. 2 is a sectional view taken generally along the line Il-Il of FIG. 1;

FIG. 3 is an enlarged view of part of the tap changer switch seen in FIG. 1;

FlG. 4 is an enlarged sectional view of the contacts in the closed position, the movable contact structure being shown in two other positions in dot and dash lines;

FIG. 5 is a partial plan view of one of the movable contact arms;

FIG. 6 is an enlarged elevational view of one of the movable contact arm structures with the shielding tube and a stationary contact structure being shown in dot-anddash lines;

PEG. 7 is a view similar to EEG. 6 of a modified form of the invention; and

FIG. 8 is a diagrammatical view showing tap connections between the ttap changer switch and the transformer winding.

Referring to the drawings, and particularly to FIG. 1 thereof, a transformer 3 comprises a housing 5 that encloses a core 7, a high voltage winding 9, a low voltage winding ill (FIG. 8), and a tap changer switch indicated generally at 13. The internal structures are immersed in a cooling and insulating fluid such as oil 1 Two bush ings 15 (only one being seen in PEG. 1) are provided to enable connection of the transformer winding 9 to a high voltage power source. The bushings l5 and winding 9 are electrically connected by means of conductors 16. Two other bushings (not shown) are electrically connected to the low voltage winding llll (FIG. 8) in a well known manner.

The tap changer switch 13 comprises four stationary insulating posts 17 (FIGS. 1 and 2) supported between two supporting plates 19 that are attached to the side walls of the housing 5. Four stationary contact structures 21, 23, 215 and 27 are supported on the insulating posts 17. As is best seen in SE68. 3 and 4, each of the stationary contact structures comprises two spaced apart rigid contact members 31 and 33 that are formed integrally with a conducting block 35 that is clamped to the insulating post 17 by means of a conducting nut 37 that is attached to the outer end of a threaded conducting bolt 39, which bolt 39 is secured to the block 35 and passes through a suitable opening in the insulating post 17. A conducting nut 45 is provided to permit connection of the stationary contact structure in an electric circuit. As can be seen in FIG. 4, the spaced apart stationary contact members 31 and 33 have curved contact surfaces 43 at opposite ends thereof that converge into main flat spaced apart contact surfaces 45.

in addition to the four stationary posts 17, the tap changer switch 13 comprises an insulating center post 47 that is rotatably supported between the supporting plates 19. A movable bridging contact structure 49, comprising two similarly constructed contact arm structures 51 and 53 (FEG. 2), is rigidly attached to the center post 47 by means of a bolt 54 that fastens two arcuate clamping members $5 and 57 to the post 4?. Each of the contact arm structures 51 and 53 comprises a rigid supporting block 59 that is welded or otherwise suitably secured to the clamp 57.

Since the contact arm structures 51 and 53 (FIG. 2) are of similar construction, only the contact arm structure Sl will be specifically described. Referring to FIG. 6, the contact arm structure 51 comprises the supporting block 59 that is rigidly secured to the clamp portion 57. Two elongated flat springs 63 are fastened to the supporting block 59 by means of a rivet 65. Two elongated flat flexible conductors 67 are fastened to the supporting block 59 by means of a rivet 68 that also fastens two conducting connectors 69 to the block 59. The conducting connectors 69 electrically connect the conductors 67 (FIG. 2) of the adjacent contact arm structures 51 and 53.

Referring to FIG. 5, each of the elongated springs 63 and elongated conductors 67 is split at the outer end thereof to provide two relatively movable leg portions each of which has a contact 76 secured thereto. A coil type spring '71 (FIG. 6) is secured under initial compression between the elongated springs 63 by means of a rivet structure '73. The conductors 67 and springs 63 are fastened together at their free or outer ends by means of rivets 74. When electrical shielding is necessary due to high voltages, a shielding tube of, for example, aluminum is provided.

The center post 4'7 is rotated, to rotate the movable contact structure 49, by means of an enclosed gear mechanism 79 (FIG. 1) having an operating rod 81 extending therefrom to an external manually operable hand wheel 83. A motor mechanism could be connected to the rod 81 to operate the tap changer switch.

Referring to FIG. 8, it can be seen that the stationary contact structures 21, 23, 25 and 2.7 are connected to different parts of the high voltage winding 9 by means of conductors Ll, L2, L3 and L4, respectively. With the movable contact arm structures 51 and 53 engaging the stationary contacts 25 and 23 respectively, the total high 3 voltage winding 9 is electrically energized. In order to adjust the amount of the high voltage winding 9 in the circuit, the winding 9 is first (ls-energized. by operation of a circuit interrupter (not shown) and the hand wheel 83 (FIG. 1) is then rotated to rotate the center post 47 and, therefore, the movable contact structure 49 to a position Where the bridging contact arm structures 51 and 53 bridge any two other adjacent stationary contact structures.

As can be seen in FIGJ 4, as each of the movable contact structures 51, 53 approaches one of the stationary Contact structures, if the movable contact arm structure is not in perfect alignment with the stationary contact structure, one of the contacts 76 will engage one of the converging surfaces 43' whereupon the elongated springs 63 (FIG. 6) of the movable contact arm structure will be deflected until the movable contact structure is properly aligned with opposite contacts 763 engaging opposite converging surfaces 43. The spring rate of the coil spring 71 is high enough so that the springs 63 simultaneously deflect into the properly aligned position Without eflecting compression of the spring71. The dimension between the outer surfaces of opposite contact buttons 70 is greater than the dimension between the main contact surfaces 45 of the stationary contact structure. Thus, when the contact arm structure is in proper alignment with the opposite contacts 70 engaging the opposite converging contact surfaces 43 (FIG. 4), the opposite contacts 7%, upon further closing movement of'the contact arm structure, will be cammed together to additionally compress the pre-charged coil spring 71. In the closed position, the compressed coil spring 71 biases the contacts 79 into engagement with the main contact surfaces 45 to maintain contact pressure. 7

During a subsequent operation of the tap changer switch 13, as the contacts are separated, the contacts 70 engage the (now describedas diverging) contact surfaces 43 to permit the coil spring 71 to gradually expand to its initial pre-charged (FIG. 6) condition and to permit the elongated springs 63 to unflex back to the normal position seen in FIG. 6. If either-of the contact arm structures is out of perfect alignment with any of the other stationary contact structures during subsequent operations, the contacts will close in substantially the sam manner as that previously described.

It is not critical that the coil spring 7 1 be placed under initial compression. The operation of the'contact structures will be substantially the same if the coil spring 71 is placed in the normal position in an uncharged condition so long as the spring 71 is long enough that it will be charged as the contacts '70 are moved into engagement with the main contact surfaces 45.

Another embodiment of the invention is shown in FIG. 7 wherein a movable contact arm structure 51 comprises elongated fiat springs 85 that are secured to the supporting block 59 by means of a rivet S7. The outer ends of the springs 85 are connected to a rigid supporting and connecting block 89 by means of a rivet 91. Shorter flat springs 93 are attached to the block 89 by means of a rivet 95. Elongated flat flexible conductors 97 similar to the conductors 67, except for a bent portion 99pmvided to clear the rivet-s 91 and 95, are secured at one end to the supporting block 59. Contacts 101 are provided at the outer or free ends of the conductors 97. The conductors 97 and springs 93 are fastened together at theirfree ends by means of rivets M2. The movable contact structure 51 is part of a movable contact structure that is similar to the contact structure 49 seen in FIGS. 1-6 and 8 except that the contact arm structures 51, 53 are modified in the manner illustrated in FIG. 7. In this embodiment of the invention, the elongated springs 85 which have a spring rate of about to of the spring rate of the shorter springs 93, first deflect as a unit to provide contact alignment in the same general manner previously described, and, when the contacts are aligned,

as the contact arm structures. are moved into the fully closed position, the shorter springs 93 are flexed to pro vide contact pressure between the contacts 1M and the main contact surfaces 45 (FIG. 4).

From the foregoing, it can be understood that there is provided by this invention an improved switch structure with improved means for aligning spaced apart contacts of a movable contact structure with spaced apart contacts of a stationary contact structure, and for effecting contact pressure as the contacts are brought into the fully closed position. The switch structure comprises two electrically connected bridging contact arm structures that engage adjacent stationary cont cts of a plurality of stationary contact structures to connect a selected number of turns in a Winding circuit to thereby permit regulation of the output voltage of a transformer. In the drawings, a singie tap changing switch is shown and described. It can be understood that a plurality of similar tap changing switches, mounted, for. example, in a vertical relationship, could be operated by rotation of the single center post. 7

Since numerous changes may be made in the above described construction, and different embodiments of the invention may be'made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In an electric switch structure, a stationary contact structure'comprising a pair of spaced apart surfaces converging into spaced apart main contact surfaces, a movable contact structure comprising a pair of spaced apart flexible conductors, contacts disposed. on opposite sides of said pair of conductors and cooperable with said main contact surfaces, a support, means for moving said support to move said movable contact structure to move said contacts in thedirection of convergence of said converging surfaces and into a closed position in engagement With 2. An electric switch structure comprising, in combination, a stationary contact structure comprising a pair of spaced apart surfaces converging into spaced apart main contact surfaces, said main contact surfaces comprising generally planar surfaces disposed along generally parallel planes, a movable and elongated contact structure comprising a pair of spaced apart elongated flexible conductors, contacts disposed on opposite sides of said pair of conductors and c ooperable with said main contact surfaces, a support, means for moving said support to move said movable contact structure along a plane generally parallel to said generally parallel planes to move said contacts in the direction of convergence of said converging surfaces and into a closed position in engagement with said main contact surfaces, said movable contact structure comprising a first spring means and a second spring means, said first spring means supporting said contacts on said support and flexing when one of said contacts engages one of said converging surfaces to align said contacts with said main contact surfaces, said second spring means being disposed between said flexible conductors and operating when said contacts are moved into said closed position to bias said flexible conductors in opposite directions to thereby bias said spacedapart contacts in opposite directions, the dimension between said main contact surfaces being less than the dimension between the contact engaging surfaces of said opposite movable contacts whereby as said movable contact structure is moved into said closed position said second spring means is compressed to effect contact pressure between said movable contacts and said main contact surfaces.

3. In an electric switch structure, a stationary contact structure comprising a pair of spaced apart surfaces converging into spaced apart main contact surfaces, 21 movable contact structure comprising a pair of spaced apart flexible conductors, contacts disposed on opposite sides of said pair of conductors and cooperable with said main contact surfaces, means for moving said movable contact structure to move said contacts in the direction of convergence of said converging surfaces and into a closed position in engagement with said main contact surfaces, a first spring means comprising two elongated springs disposed one adjacent each of said conductors and flexing when one of said contacts engages one of said converging surfaces to align said contacts with said main contact surfaces, and a coil type spring disposed between said spac d apart flexible conductors and biasing said conductors to bias said contacts against said main Contact surfaces.

In an electric switch structure, a stationary contact structure comprising a pair of spaced apart surfaces converging into spaced apart main Contact surfaces, a movable elongated contact structure comprising a pair of spaced apart flexible conductors, contact means secured to each of said conductors and cooperable with said main Contact surfaces, a support, means for moving said support to move said movable contact structure to move said contact means in the direction of convergence of said converging surfaces and into a closed position in engage ment with said main contact surfaces, said movable contact structure comprising a first spring means and a second spring means, said first spring means supporting said contact means on said support and flexing when one of said contact means engages one of said converging surfaces to align said contact means with said main contact surfaces, said second spring means comprising a coil spring disposed between said flexible conductors under initial compression and biasing said flexible conductors apart, means limiting the movement apart of said flexible condoctors, the dimension between said flexible conductors being such that as said movable contact structure is moved into the fully closed position said coil spring is additionally charged to provide contact pressure between said contact means and said main Contact surfaces.

5. An electric switch structure comprising, in combination, a stationary Contact structure comprising a pair of spaced apart surfaces converging into spaced apart main contact surfaces, a movable contact structure comprising a pair of spaced apart flexible conductors, contacts disposed on opposite sides of said pair of conductors and c0- operable with said main contact surfaces, means for moving said movable contact structure to move said contacts in the direction of convergence of said converging surfaces and into a closed position in engagement with said main contact surfaces, a first spring means comprising elongated llat springs disposed one spring adjacent each of said conductors, said first spring means flexing when one of said contacts engages one of said converging surfaces to thereby said contacts with said main contact surfaces, and a second spring means comprising a pair of flat springs separate from said first spring means and positioned one adjacent each of said flexible conductors, and said second spring means operating when said contacts are moved into said closed position to bias said contacts in opposite directions against said main contact surfaces.

6. In an electric s vitch structure, a first contact structure comprising a pair of spaced apart Contact members having surfaces converging into main spaced apart contact surfaces, a second contact structure comprising a support member and a pair of spaced apart elongated flexible conducting arms each of which arms is secured at one end thereof to said support member, contacts disposed on opposite sides of the free ends of said conducting arms and cooperable with said main contact surfaces, a first spring means comprising two elongated springs each of which is secured at one end thereof to said support member and each of which is positioned adjacent one of said conducting arms, a connecting support, the other ends of said springs being secured to said connecting support, said first spring means flexing when one of said contacts engages one of said converging surfaces to align said contacts with said main contact surfaces, a second spring means comprising a pair of elongated springs each of which is connected at one end to said connecting support and each of which is positioned adjacent one of said conducting arms, said sccond spring means operating when said contacts are moved into said closed position to bias said contacts against said main contact surfaces.

"7. An electric switch structure comprising, in combination, a stationary contact structure comprising a pair of spaced apart contact members having surfaces converging into main spaced apart contact surfaces, a movable contact structure comprising a support member and a pair of spaced apart elongated conducting arms each of which is secured at one end thereof to said support member, contact means disposed on the free end of each of said conducting arms, a first spring means comprising a pair of elongated fiat spring members each of which is secured at one end to said support member and each of which is positioned adjacent one of said conducting arms, a connecting support, each of said elongated spring members being secured at the other end thereof to said connecting support, a second spring means comprising a pair of elongated liar springs each of which is secured at one end thereof to said connecting support, each of the springs of said second spring means being positioned adjacent one of said conducting arms in proximity to the contact carrying end of the conducting arm, the spring rate of said second spring means being more than twice the spring rate of said first spring means, said first spring means flexing when one of said contacts engages one of said converging surfaces to align said contacts with said main contact surfaces, and said second spring means being flexed when said contact structure is moved into the fully closed position to provide contact pressure between said contacts and said main contact surfaces.

8. A tap changer switch adapted to be connected to a transformer winding, said tap changer switch comprising a plurality of stationary contact structures, a movable contact structure comprising two movable contact arm structures electrically connected and adapted to simultaneously engage two dilferent stationary contact structures to bridge said stationary contact structures, each of said stationary contact structures comprising a pair of spaced apart urfaces converging into spaced apart main contact surfaces, each of said movable contact arm structures comprising a pair of spaced apart conductors, a separate pair of contacts disposed on opposite sides of each of said pairs of conductors, each of said pairs of contacts being cooperable with said pairs of main contact surfaces, a support, means for moving said support to move said movable contact structure to move said pairs of contacts in the direction of convergence of said converging surface to thereby move each of said pairs of contacts into a closed position in engagement with be associated main contact surfaces, each of said movable contact arm structures comprising a first spring means and a second spring means, each of said first spring means supporting the associated pair of contacts on said support and flexing when one of the contacts of the associated pair of contacts engages one of said converging surfaces to align the associated pair of contacts with the associated main contact surfaces, and each of said second spring means being disposed between the associated pair of conductors and operating when the associated pair of contacts is moved into said closed position to bias the associated pair of conductors apart to thereby bias the contacts of the associated paircf contacts against the associated main contact surfaces.

9. A tap changer switch adapted to be connected to a transformer winding, said tap changer switch comprising a plurality of stationary contact structures, a movable contact structure comprising two movable contact arm structures electrically connected and adapted to simultaneously engage two difiierent stationary contact structures to bridge said stationary contact structures, each of said stationary contact structures comprising a pair of spaced apart urfaces converging int-o spaced apart main contact surfaces and then diverging away from said spaced apart main contact surfaces, said main contact surfaces comprising generally parallel planar main contact surfaces, each of said movable contact structures comprising a pair of spaced apart conductors, a separate pair of contacts disposed on opposite sides of each of said pairs of conductors, a support rotatable about an axis generally normal to the planes of said main contact surfaces, means for rotating said support to move said movable contact structure to move said pairs of contacts in the direction of convergence of said converging surfaces to thereby move each of said pairs of contacts into a closed position inengagement with the associated main contact surfaces, each of said movable contact arm structures comprising a first spring means and a second spring means, each of said first spring means supporting the associated pair of contacts on said support and flexing when one of the contacts of the associated pair of con tacts engages one of said converging surfaces to align the associated pair of contacts with the associated main contact surfaces, and each of said second spring means being disposed between the associated pair of conductors and operating when the associated pair of contacts is moved into said closed position to bias the associated" pair of conductor apart to thereby bia the contacts of the associated pair of contacts apart and against the associated main contact surfaces.

10. A transformer tap changer switch comprising, in combination, a plurality of stationary contact structures, a movable contact structure comprising a pair of contact arm structures electrically connected and movable in unison, said movable contact structure when in the closed position bridging two of said stationary contact structures, each of said stationary contact structures comprising a pair of spaced apart surfaces converging into spaced apart main contact surfaces, each of said movable contact arm structures comprising a pair of spaced apart flexible conductors, contact means disposed on opposite sides of each of saidpairs of conductors and cooperable with said main contact surfaces, means for moving said movable contact structure to move said contact means in the direction' of convergence of said converging surfaces into a closed position in engagement with said main contact surfaces, each of said contact arm tructures comprising a first spring means comprising two flat springs disposed one adjacent each of said flexible conductors, said first spring means flexing when the'associated contact means engages one of said converging surfaces to align the contact means with the associated main contact surfaces, and

, each of said contact arm structures comprising a second spring means comprising a coil type spring biasing the associated flexible conductors apart to provide contact pressure when the associated contact means is in the closed position.

11. In a transformer tap changer, the combination com prising a plurality of stationary'contact structures, a movable contact structure comprising two electrically connected elongated contact arm structures for bridging two a of said stationary contact structures, each of said movable contact arm structures comprising a pair of flexible conductors, .a contact disposed on each of two opposite sides of each of said pair of conductors, means for moving said movable contact structure to move said contacts in the direction of convergence of said converging surfaces and into aclosed position in engagement with said main contact surfaces, a first spring means for each of said contact arm structures and comprising a pair of elongated fiat springs each of which is secured at one end to a support member and is disposed adjacent one of said conductors, each of said first spring means flexing when one of said contacts engages one of said converging surfaces to align the associated contacts with the associated main contact surfaces, a connecting support for each of said contact arm structures, the other ends of said flat springs being connected to the associated connecting support, a second spring means for each of said contact arm structures and comprising a pair of elongated fiat springs each of which References Cited by the Examiner UNITED STATES PATENTS 2,510,051 6/50 De Montrnollin et al. "00-470 ROBERT K. SCHAEFER, Acting Primary Examiner. BERNARD A, GILHEANKEraminer. 

1. IN AN ELECTRIC SWITCH STRUCTURE, A STATIONARY CONTACT STRUCTURE COMPRISING A PAIR OF SPACED APART SURFACES CONVERGING INTO SPACED APART MAIN CONTACT SURFACES, A MOVABLE CONTACT STRUCTURE COMPRISING A PAIR OF SPACED APART FLEXIBLE CONDUCTORS, CONTACTS DISPOSED ON OPPOSITE SIDES OF SAID PAIR OF CONDUCTORS AND COOPERABLE WITH SAID MAIN CONTACT SURFACES, A SUPPORT, MEANS FOR MOVING SAID SUPPORT TO MOVE SAID MOVABLE CONTACT STRUCTURE TO MOVE SAID CONTACTS IN THE DIRECTION OF CONVERGENCE OF SAID CONVERGING SURFACES AND INTO A CLOSED POSITION IN ENGAGEMENT WITH SAID MAIN CONTACT SURFACES, SAID MOVABLE CONTACT STRUCTURE COMPRISING A FIRST SPRING MEANS AND A SECOND SPRING MEANS, SAID FIRST SPRING MEANS SUPPORTING SAID CONTACTS ON SAID SUPPORT AND FLEXING WHENN ONE OF SAID CONTACTS ENGAGES ONE OF SAID CONVERGING SURFACES, AND SAID SECOND TACTS WITH SAID MAIN CONTACTS SURFACES, AND SAID SECOND SPRING MEANS BEING DISPOSED BETWEEN SAID FLEXIBLE CONDUCTORS AND OPERATING WHEN SAID CONTACTS ARE MOVED INTO SAID CLOSED POSITION TO BIAS AND FLEXIBLE CONDUCTORS APART TO THEREBY BIAS SAID CONTACTS IN OPPOSITE DIRECTIONS AGAINST SAID MAIN CONTACT SURFACES. 